refactor(app): compose settings and developer tools

src/AcDream.App/Settings/RuntimeKeyBindingTarget.cs

@@ -0,0 +1,45 @@
+using AcDream.UI.Abstractions.Input;
+
+namespace AcDream.App.Settings;
+
+internal interface IRuntimeKeyBindingTarget
+{
+    void Apply(KeyBindings bindings);
+}
+
+/// <summary>
+/// Applies a settings-panel keymap to the live dispatcher and then persists
+/// that exact map. Persistence failure is reported without rolling back the
+/// already accepted live binding, matching the former startup-root callback.
+/// </summary>
+internal sealed class RuntimeKeyBindingTarget : IRuntimeKeyBindingTarget
+{
+    private readonly InputDispatcher _dispatcher;
+    private readonly string _path;
+    private readonly Action<string> _log;
+
+    public RuntimeKeyBindingTarget(
+        InputDispatcher dispatcher,
+        string? path = null,
+        Action<string>? log = null)
+    {
+        _dispatcher = dispatcher ?? throw new ArgumentNullException(nameof(dispatcher));
+        _path = path ?? KeyBindings.DefaultPath();
+        _log = log ?? Console.WriteLine;
+    }
+
+    public void Apply(KeyBindings bindings)
+    {
+        ArgumentNullException.ThrowIfNull(bindings);
+        _dispatcher.SetBindings(bindings);
+        try
+        {
+            bindings.SaveToFile(_path);
+            _log($"keybinds: saved to {_path}");
+        }
+        catch (Exception failure)
+        {
+            _log($"keybinds: save failed: {failure.Message}");
+        }
+    }
+}